In the field of micromechanics, mechanical devices are produced which are on the scale of micrometers (i.e., approximately 1.times.10.sup.-6). In particular, electrically powered micrometer-sized micro-motors (or "micro-engines" as they are known) exist which provide rotational motion in order to drive a mechanical load. While micromotors, such as disclosed in U.S. Pat. No. 5,631,514, titled "Microfabricated Microengine for Use as a Mechanical Drive and Power Source in the Microdomain and Fabrication Process," are sufficient to drive a mechanical load at micrometer scale, such devices cannot drive larger mechanical loads such as may exist in the millimeter domain (i.e., approximately 1.times.10.sup.-3). While a variety of high-aspect ratio electrostatic and magnetic micro-motors have been constructed using LIGA processing ("Lithographie Galvanoforming Abforming", an acronym which evolved from the Karlsruhe Nuclear Research Center in Germany), there is a need for millimeter sized devices in situations where micromachined devices cannot provide sufficient torque because they are generally too small and where conventionally fabricated motors are not available in the millimeter scale.
Millimachinery (also known as mesoscopic machinery), as used in the present invention, refers to machining of an intermediate range of devices which fit between the dimensions of micromachined devices (which are perceivably small to the human eye) and those devices which are large enough to be conventionally fabricated. In particular, millimachined devices fill a gap which allows micromachined devices to interface with large scale, conventionally fabricated, devices. When devices are fabricated in this intermediate range, magnetic actuation provides higher energy densities than that provided by electrostatic actuation, and therefore, is one reason a magnetic actuation scheme is the preferred design. While micromachined devices may be difficult to package during manufacturing due to the small sizes inherent in such devices, millimachined devices may assist implementing micromachined devices when packaging becomes a manufacturing constraint.
Recent advances in micromachining technology (including surface micromachining and LIGA processes) permit fabrication of millimeter structures which can be used in machinery for applications which require positioning, material manufacturing (including milling, drilling and cutting), pumping, medical applications, optical switching and other applications. Each application requires mechanical power for operation. As described in the article titled "Surface Micromachined Microengine", E. J. Garcia, J. J. Sniegowski, Sensors and Actuators, A 48, pp. 203-214 (1995), recent advances in surface micromachining have lead to the development of electrostatic actuators capable of driving microscopic machinery. However, machinery that is sized several orders of magnitude larger, i.e., to the order of millimeters, cannot be powered by these recently developed surface micromachined devices. Micrometer devices are unable to produce sufficient force and/or torque to drive the larger machinery. Therefore, one of the novel features of the present invention is that it is capable of providing the required force and torque needed to drive millimachinery. Moreover, a modified LIGA process employed to manufacture millimeter sized components enables the fabrication of such components in sizes that cannot be achieved by either surface micromachining or conventional miniature machining.
The millimeter-sized invention disclosed herein differs from existing micromachined devices in several respects. First, until the present invention, devices did not exist which were fabricated by millimachining methods to achieve functional components which are both sized and operate in the millimeter range. Second, millimeter fabricated devices are capable of driving larger mechanical loads than the same number of micromachined devices. Third, unlike micromachined devices, millimeter fabricated devices are capable of generating a greater amount of torque.
It is therefore an object of the present invention to provide a milliengine machined and adapted to operate between the dimensions of smaller micromachined devices which are perceivably small to the human eye and those devices which are large enough to be conventionally fabricated.
It is a further object of the present invention to provide a milliengine adapted to convert electromagnetic energy to mechanical energy through various structural elements, for connection to an external mechanical load.
It is also an object of the present invention to provide a motor sized in the millimeter scale adapted to convert linear motion to rotary motion by use of actuators which operate out of phase with each other, to deliver positive torque to at least one output gear.
It is a further object of the present invention to disclose a motor sized in the millimeter scale which includes a plurality of electromagnetic circuits adapted to control a plurality of structural elements to drive an external mechanical load.
It is an object of the present invention to provide a electromechanical millimetersized machine adapted for precision control of external positioning, handling, aligning, sorting, sensing, cutting, slicing, material removal and pumping devices.
It is an object of the present invention to provide a electromechanical millimetersized millimachine for use in biomedical applications which require pumping performed inside a body.
It is also an object of the present invention to provide a device sized in the millimeter domain adapted to power millimeter sized valves, optical shutters, electrical switches and relays, miniature hard disk drives, miniature robotic devices, and fiber optic switching and scanning devices.
It is a further object of the present invention to provide a milliengine capable of operating and controlling any application requiring movement or application of forces or torque to millimeter or micrometer sized devices.
It is an object of the present invention to provide a electrically isolated device for use in an aqueous environment where electromagnetic power is transferred to a mechanical output through a fixed and sealed magnetic flux path that passes through a substrate from the isolated electrical elements on the backside of the substrate to the exposed mechanical elements on the top side of the substrate.